A method for synthesizing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline

Abstract

The present invention discloses a method for synthesizing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline. The method uses 2-methyl-6-ethylaniline and 1-methoxy-2-propanone as raw materials, and reacts in a hydrogen atmosphere under the action of a catalyst to produce 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline. The catalyst is Pt / Al 2 O 3 catalyst, and in the Pt / Al 2 O 3 catalyst, the Pt loading is 0.01% to 1%. The present invention can greatly reduce the cost of industrially producing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline.

Description

Technical Field

[0001] The present invention relates to the field of pesticide production, and particularly relates to a preparation method of 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline. Background Art

[0002] Metolachlor is an amide herbicide, which has the advantages of high safety, wide range of applicable crops, large production scale, etc. It is low in toxicity itself and has little environmental pollution, and inhibits cell growth by hindering protein synthesis.

[0003] The chemical name of the intermediate of metolachlor is 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline, and its structural formula is Formula 1

[0004]

[0005] The synthesis process of the intermediate of metolachlor is that after mixing 2-ethyl-6-methylaniline with 1-methoxy-2-propanone, a catalyst is added, and H 2 is introduced, the reaction temperature is set, and the product obtained is 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline. The reaction equation is shown in Equation 1

[0006]

[0007] At present, precious metals such as Pd and Pt used in industry are expensive. Common recovery methods include acid dissolution method, alkali dissolution method, chlorination leaching method, etc. The recovery steps are numerous, the recovery cost is high, and the secondary utilization rate of precious metals is low. The catalyst used in the industrial production of the intermediate of metolachlor is a mixture of Pd / C and Pt / C. Pd and Pt belong to the same group of elements. To recover Pd and Pt from waste Pd / C and Pt / C catalysts, usually SO 2 is introduced. Using its reducibility, a crude product metal slag is obtained. Since Pd and Pt are mixed, it is necessary to go through multiple steps of reaction to obtain the precipitates Pd and Pt respectively, and the highest recovery rate is 50%, and the recovery utilization rate is low. Summary of the Invention

[0008] In order to solve the problems occurring in the above-mentioned prior art, the present invention provides a method for synthesizing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline with an ultra-low Pt loading amount to reduce the production cost.

[0009] To solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A method for synthesizing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline, which uses 2-methyl-6-ethylaniline and 1-methoxy-2-acetone as raw materials and reacts in a hydrogen atmosphere under the action of a catalyst to produce 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline; the reaction formula is as follows:

[0011]

[0012] The catalyst is a Pt / Al 2 O 3 catalyst, and in the Pt / Al 2 O 3 catalyst, the Pt loading is 0.01% to 1%. The preparation steps of the Pt / Al 2 O 3 catalyst are as follows:

[0013] (1) Dissolve chloroplatinic acid hexahydrate and deionized water to form an aqueous solution of chloroplatinic acid;

[0014] (2) Place the Al 2 O 3 support in a container, slowly drop an appropriate amount of the aqueous solution of chloroplatinic acid, and let it stand for 12 - 24 h after dropping;

[0015] (3) Dry the mixture after standing in an oven at 100 - 150 °C for 4 - 6 h to obtain a dried product;

[0016] (4) Calcinate the dried product in a muffle furnace at 400 - 550 °C for 4 - 6 h to obtain a calcined product;

[0017] (5) Reduce the calcined product in a tubular furnace at 500 - 600 °C for 2 - 6 h under H 2 to obtain the Pt / Al 2 O 3 catalyst.

[0018] In the step (2), the dropping amount of the aqueous solution of chloroplatinic acid is calculated according to the complete loading of Pt in the aqueous solution of chloroplatinic acid onto the support.

[0019] Preferably, in the Pt / Al 2 O 3 catalyst, the Pt loading is 0.01% to 0.1%.

[0020] Preferably, the method for synthesizing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline is specifically implemented as follows: Add 2-methyl-6-ethylaniline, 1-methoxy-2-acetone, and Pt / Al 2 O 3 catalyst into a reaction kettle, and introduce N2 Replace the air and then introduce H 2 Replace N 2 , control the hydrogen pressure to be 1-6 MPa and the temperature to be 30-90 °C for reaction. After sufficient reaction, 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline is obtained.

[0021] Preferably, the molar ratio of 2-methyl-6-ethylaniline to 1-methoxy-2-propanone is 1:1.6-1.8.

[0022] Preferably, the mass dosage of the Pt / Al 2 O 3 catalyst is 0.5-7.5% of the mass dosage of the raw material 2-methyl-6-ethylaniline, more preferably 2.5-5%, and even more preferably 4.5-5%.

[0023] Preferably, the reaction time is 1-6 h.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The method for synthesizing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline using the Pt / Al 2 O 3 catalyst with a low Pt loading amount has the advantages of high conversion rate, high product selectivity, less three-waste discharge, and a clean and pollution-free process. Moreover, the Pt / Al 2 O 3 catalyst is simple to prepare, has a small Pt metal loading amount, can be recycled, and the Pt in the waste catalyst is easy to recover, thereby greatly reducing the cost of industrially producing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline. Detailed implementation manners

[0026] In order to better understand the technical solution of the present invention, the technical solution provided by the present invention will be described in detail below with reference to specific embodiments. However, the scope of protection required by the present invention is not limited to the scope described in the embodiments.

[0027] Example 1: Preparation of 0.1% Pt / Al 2 O 3 catalyst

[0028] (1) Weigh 13.27 g of chloroplatinic acid hexahydrate and prepare an aqueous solution of chloroplatinic acid with deionized water, with a platinum concentration of 0.05 g / ml.

[0029] (2) Weigh 4.995 g of Al 2 O 3 support (purchased from Macklin reagent platform), and add Al 2 O3 The carrier was placed in a glass dish, and 100 μl of an aqueous solution of chloroplatinic acid hexahydrate was slowly added dropwise using a pipette, and then left to stand in a fume hood for 24 h.

[0030] (3) After standing, it was dried in an oven at 100 °C for 4 h.

[0031] (4) After drying, it was calcined in a muffle furnace at 500 °C for 4 h.

[0032] (5) After calcination, it was reduced with hydrogen at 550 °C for 2 h in a tubular furnace to obtain 0.1% Pt / Al 2 O 3 catalyst, which was used in the subsequent examples.

[0033] Example 2: Preparation of 1% Pt / Al 2 O 3 catalyst

[0034] (1) Weigh 13.27 g of chloroplatinic acid hexahydrate and dissolve it in deionized water to prepare an aqueous solution of chloroplatinic acid with a platinum concentration of 0.05 g / ml.

[0035] (2) Weigh 4.95 g of Al 2 O 3 carrier (purchased from Macklin reagent platform), and place the Al 2 O 3 carrier in a glass dish, and slowly add 1000 μl of the aqueous solution of chloroplatinic acid hexahydrate dropwise using a pipette, and then leave to stand in a fume hood for 24 h.

[0036] (3) After standing, it was dried in an oven at 100 °C for 4 h.

[0037] (4) After drying, it was calcined in a muffle furnace at 500 °C for 4 h.

[0038] (5) After calcination, it was reduced with hydrogen at 550 °C for 2 h in a tubular furnace to obtain 1% Pt / Al 2 O 3 catalyst, which was used in the subsequent examples.

[0039] Example 3:

[0040] (1) Add 13.521 g (0.1 mol) of 2-methyl-6-ethylaniline, 14.0976 g (0.16 mol) of 1-methoxy-2-propanone, and 0.45 g of 0.1% Pt / Al 2 O 3 to a reaction kettle, seal the reaction kettle, purge it three times with N 2 , and then purge it three times with H 2 . The pressure of H 2 is 1.6 Mpa, and the reaction is carried out at 70 °C for 2 h.

[0041] (2) After the reaction is completed, wait for the temperature in the reaction kettle to drop to room temperature, take out the product liquid from the liquid phase valve, and discharge the excess H from the gas phase valve. 2 , and the product was detected by a FULI 9790 gas chromatograph. A DB-1 non-polar low-loss chromatographic column was used, the column temperature was 80 °C, the temperature rising condition: 15 °C / min, the vaporization chamber temperature was 250 °C, the detector temperature was 250 °C, the retention time was 15 min, and the gas phase result was a selectivity of 55.6%.

[0042] Example 4:

[0043] (1) Add 13.521 g (0.1 mol) of 2-methyl-6-ethylaniline, 14.0976 g (0.16 mol) of 1-methoxy-2-propanone, and 0.65 g of 0.1% Pt / Al 2 O 3 to the reaction kettle, close the reaction kettle, and introduce N from the gas phase valve 2 and displace three times, then introduce H 2 and displace three times, the pressure of H 2 is 1.6 Mpa, and react at 70 °C for 2 h.

[0044] (2) After the reaction is completed, wait for the temperature in the reaction kettle to drop to room temperature, take out the product liquid from the liquid phase valve, and discharge the excess H from the gas phase valve. 2 , and the product was detected by a FULI 9790 gas chromatograph. A DB-1 non-polar low-loss chromatographic column was used, the column temperature was 80 °C, the temperature rising condition: 15 °C / min, the vaporization chamber temperature was 250 °C, the detector temperature was 250 °C, the retention time was 15 min, and the gas phase result was a selectivity of 74.09%.

[0045] Example 5:

[0046] (1) Add 13.521 g (0.1 mol) of 2-methyl-6-ethylaniline, 14.0976 g (0.16 mol) of 1-methoxy-2-propanone, and 0.4 g of 1% Pt / Al 2 O 3 to the reaction kettle, close the reaction kettle, and introduce N from the gas phase valve 2 and displace three times, then introduce H 2 and displace three times, the pressure of H 2 is 1.6 Mpa, and react at 70 °C for 2 h.

[0047] (2) After the reaction is completed, wait for the temperature in the reaction kettle to drop to room temperature, take out the product liquid from the liquid phase valve, and discharge the excess H from the gas phase valve. 2The product was detected by FULI9790 gas chromatograph, using DB-1 non-polar low-bleed chromatographic column, column temperature 80°C, heating conditions: 15°C / min, vaporization chamber temperature 250°C, detector temperature 250°C, retention time 15min, and the gas phase result was a selectivity of 84.56%.

[0048] Comparative Example 1:

[0049] (1) 13.521 g (0.1 mol) of 2-methyl-6-ethylaniline, 14.0976 g (0.16 mol) of 1-methoxy-2-acetone, 0.15 g of 5% Pt / C, and 0.15 g of 5% Pd / C (Pt / C was purchased from Anaiji Platform, and Pd / C was purchased from Aladdin Platform) were added to the reactor, the reactor was sealed, and N 2 Replace three times, then pass H 2 Replace three times, H 2 The pressure was 1.6 MPa and the reaction was carried out at 70°C for 2 hours.

[0050] (2) After the reaction is completed, wait until the temperature in the reactor drops to room temperature, take out the product liquid from the liquid phase valve, and discharge the excess H from the gas phase valve. 2 The product was detected by FULI9790 gas chromatograph, using DB-1 non-polar low-bleed chromatographic column, column temperature 80°C, heating conditions: 15°C / min, vaporization chamber temperature 250°C, detector temperature 250°C, retention time 15min, and the gas phase result was a selectivity of 91.23%.

[0051] The cost comparison analysis of the catalyst in the present invention and the current industrial catalyst is shown in Table 1 below.

[0052] Table 1

[0053]

[0054] Note: Chloroplatinic acid hexahydrate 478.4 yuan / g (purchased from McLean reagent platform),

[0055] Palladium chloride 927.9 yuan / g (purchased from Sinopharm reagent platform),

[0056] Alumina 1 yuan / g (purchased from MacLean reagent platform),

[0057] Activated carbon 0.5 yuan / g (purchased from Anage reagent platform).

[0058] From the cost comparison in Table 1, it can be seen that the application cost of the catalyst of the present invention in the synthesis of 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline is much lower than the combination of Pd / C and Pt / C currently used in industry.

Claims

1. A method for synthesizing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline, which uses 2-methyl-6-ethylaniline and 1-methoxy-2-propanone as raw materials and reacts in a hydrogen atmosphere under the action of a catalyst to produce 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline; the reaction formula is as follows: Characterized in that: The catalyst described is Pt / Al 2 O 3 catalyst. In the Pt / Al 2 O 3 catalyst, the Pt loading is 0.1%. The preparation steps of the Pt / Al 2 O 3 catalyst are as follows: (1) Dissolve chloroplatinic acid hexahydrate in deionized water to form an aqueous solution of chloroplatinic acid; (2) Place the Al 2 O 3 support in a container, slowly add dropwise an appropriate amount of aqueous chloroplatinic acid solution, and let it stand for 12 - 24 h after the addition is completed; (3) The mixture after standing is dried in an oven at 100-150 °C for 4-6 h to obtain a dried product; (4) The dried product is calcined in a muffle furnace at 400-550 °C for 4-6 h to obtain a calcined product; (5) The calcined product is reduced in a tubular furnace at 500 - 600 °C for 2 - 6 h in H 2 to obtain the Pt / Al 2 O 3 catalyst; The mass dosage of the Pt / Al 2 O 3 catalyst is 4.5-5% of the mass dosage of the raw material 2-methyl-6-ethylaniline.

2. The method according to claim 1, Characterized in that: The method for synthesizing 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline is specifically implemented as follows: 2-methyl-6-ethylaniline, 1-methoxy-2-propanone, and Pt / Al 2 O 3 catalyst are added to the reaction kettle, and N 2 is introduced to displace air, and then H 2 is introduced to displace N 2 . The reaction is carried out under a hydrogen pressure of 1-6 MPa and a temperature of 30-90 °C. After sufficient reaction, 2-ethyl-N-(2-methoxy-1-methylethyl)-6-methylaniline is obtained.

3. The method according to claim 2, Characterized in that: The reaction time is 1-6 h.

4. The method according to claim 1, Characterized in that: The molar ratio of the feed of 2-methyl-6-ethylaniline and 1-methoxy-2-propanone is 1:1.6-1.8.

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